Cadillac 2010 CTS Sport Sedan Owner's Manual page 320

If the engine is warm or hot, the
coolant level should be at or above
the FROID/FULL COLD line on the
side of the coolant surge tank. If the
engine is cold, the coolant level
should be near the FROID/FULL
COLD line on the side of the coolant
surge tank. If it is not, there could
be a leak in the cooling system.
You can be burned if you spill
coolant on hot engine parts.
Coolant contains ethylene glycol
and it will burn if the engine parts
are hot enough. Do not spill
coolant on a hot engine.
An electric engine cooling fan
under the hood can start up even
when the engine is not running
and can cause injury. Keep
hands, clothing, and tools away
from any underhood electric fan.
Steam and scalding liquids from a
hot cooling system can blow out
and burn you badly. They are
under pressure, and if you turn
the surge tank pressure
cap even a little they can
come out at high speed. Never
turn the cap when the cooling
system, including the surge tank
pressure cap, is hot. Wait for the
cooling system and surge tank
pressure cap to cool if you ever
have to turn the pressure cap.
If coolant is needed, add the proper
®
DEX-COOL coolant mixture at the
coolant surge tank.
If no coolant is visible in the surge
tank, add coolant as follows:
1. Remove the coolant surge tank
pressure cap when the cooling
system, including the coolant
surge tank pressure cap and
upper radiator hose, is no longer
hot. Turn the pressure cap
slowly counterclockwise about
one-quarter turn and then stop.
If you hear a hiss, wait for that to
stop. A hiss means there is still
some pressure left.